PURIFICATION BY PRECIPITATION

Precipitation remains one of the most important of separation methods even though many other kinds of separation techniques have been discovered. Precipitation processes are characterized by simplicity of operation, efficiency of single-stage separation, and adaptability to large-scale procedure. Conventional precipitation methods do not permit the full realization of the separation potential inherent in precipitation processes. Rowever, utilization of tbe techique of precipitation from homogeneous solution permits a greater realization of this potential. Some aspects of the technique are described. Although the problem of efficient separation by a simple multi-stage solidliquid phase process hs been solved in the case of zone-melting and ion-exchange chromatography, it has not been solved for simple precipitation. Several possible means of effecting a simple multi-stage precipitation process are considered. (auth)